Fuel injection system



spt; 23, 1947. J IF, CAMIPBELL 2,427,835

FUEL INJECTION SYSTEM Filed Sept. :50, 1944 2 Sheets-Sheet 1 1105b E 602 15811 INVENTOR ATTORNEY I p J. F. CAMPBELL 2,427,835

FUEL INJECTION SYSTEM Filed Sept. 30,, 1944 2 Sheets-Sheet.2

INVENTOR BY ATTORYNEY I Patented Sept. 23,1947

UNlTED STATES V. PA TENT\ OFFICE FUEL INJECTION SYSTEM John F. Campbell,Detroit, Mich, assignor to George M. Holley and Earl Holley ApplicationSeptember 30, 1944, Serial No. 556,521

11 Claims. (Cl. 123-119) 1 The object of this invention is to improvethe fuel control apparatus as shown and described in my patent,2,281,411, dated April 28, 1942, entitled Fuel control apparatus forinternal combustion engines v Figure 1 shows diagrammatically thegeneral arrangement of the parts constituting one form of constructionof my invention.

Figure 2 shows a view taken on plane 2-! of Figure 1.

Figure 3 shows an alternative construction.

In Figure 1, i is the air entrance, II is the larger of two venturis, I2being the smaller, discharging into the throat of the larger venturi. I3is a passage connecting the throat of the small venturi with the chamberI4, which surrounds an expanding chamber IS, the inside of whichcommunicates through a passage I6 with an annular chamber I1, whichannular chamber communicates with the air entrance I0 through tubes I8which face upstream.

The expanding element I slidesa cam I0 up and down. This cam I9 engagesin the plane of the paper of the drawing with the finger 20, whichfinger 20 i partially rotated by the expansion and contraction of thepartially-evacuated chamber 21 located in the chamber 22, whichcommunicates through the passage 23 with the downstream portion of theventuri I I. The finger 20 is mounted on the lever 201 pivoted at thefulcrum 200.

In Figure 2, the end 20 of the lever MI is shown engaging with the camI3, which is pushed against the end of lever MI by a compression spring91. Can's I9 can slide vertically to the plane of the paper (Fig. 1),the end 203 of cam l8 sliding over the end of the rod 204, whichprojects from the element l5. Cam 19 also slides parallel to the planeof the paper. In Fig. 1, 24 is a passage communicating with the outletfrom the venturi ll still further downstream in the venturi II. Theleft-hand side of the cam I3 engages with the roller 25, which iscarried by a sleeve 25, which reciprocates in a block 21; this block 21has a high pressure oil entrance 20 and a low pressure exit 23.

A piston 30, having a valve portion 31, acts as a valve for a port 32.The piston engages with a compression spring 33 and the piston 30 ismechanically connected to the roller 34 carried by an arm 35. The arm 35is pushed by spring 93 so as to engage with the cam 35, which is slid upand down by an expanding and contracting chamber 31, which is responsiveto the flow of the fuel through a fuel venturi 38. Chamber 31 is locatedin a chamber 39, which is in communication with the pressure generatedby the fuel pump 40. The cam 36 thus moves up and down in response tothe expansion and contraction of the element 31. The cam 38 is movedperpendicular to the plane of the paper in response to the movement of afinger 4 I, which is rotated by a manually-controlled shaft, 42. Whenthe port 32 is in the position shown relative to the piston 3|, pressureis admitted to the passage in the pipe 43, which communicates with ahousing 44 in which there reciprocates an upper piston 45 and a lowerpiston 46 carrying a needle 41. The pipe 43 communicates through apassage 48, passage 49, passage 50 with a chamber 5i into which theneedle 41 projects through a restriction 53. The chamber 52 to the rightof the restriction 53 communicates through the pipes 54 and 18 with thelow pressure side of the oil pump 55, pipe 18 discharging into thechamber 56, into which chamber also discharges the low pressure line 29.The purpose of the low pressure line 29 is to provide a return path forthe oil discharged right and left by the pump 55. e I

The fuel from the fuel pump 40 discharges engine speed in case offour-cycle engines and at full engine speed in case of two-cycle enginesis prbvided. The lever 64 varies the effective stroke I of; the pump.

a passage 98 and a correspondingpassage 98 in the servomotor piston 65respectively-connect the chamber I00 with the right-hand side of theservomotor piston 55 and the chamber I01 with the left-hand side of theservomotor-piston 05.

A passage 102 admits high pressure oil from the pipe 0| whichcommunicates with the oil pump 55 ,to the right of the piston 65' whenservomotor .valve 81 moves to the left so that the servomotor piston 45also moves to the leiv t. At the same time, passage I03 permits oil toescape from the lefthand side of servomotor piston 05 through passage'08. When servomotor valve 01 moves to the right, high pressure oil canflow from/passage 8| through passage I02, chamber I01 and passage 98 sothat servomotor piston 6515 also moved to the right. The oil pressureescapes from the 3 right-hand side of servomotor piston 65 throughpassage 99, chamber I and passages I03 and 83 to the low pressure returnline I8. High pressure oil from the passage 55 flows through a pipe 66and enters the chamber 68 to the left of a servo piston 9| through arestriction 95.

An acceleration device comprises a cylinder and a piston 16, whichserves to move liquid in a cylinder 11 at the right of the piston. Theline I8 connects with the cylinder at the right of the piston and is thereturn low pressure line to the chamber 56 for the high pressure oilthat leaks past the piston 16 into chamber I9 to the left of the pistonI6. A high pressure passage 80 extending from chamber 11 communicatesthrough the restriction 95 with the pipe 66.

A pivot 206 for lever 85 enables the shoulder 20! to engage with thefinger 208 of the valve 46-41. A link 209 connects the lever 85 with thethrottle levers 2I0 and 2| I. The two levers 2I02I| are connectedtogether by the link 2I2. Fuel pressure lines 2I3, 2I4, 2 I5 and 2I6lead from the variable-stroke pump 63 to the fuel injection nozzles, notshown.

The throttle control lever 85 thus engages with the piston 46 and needle41 and controls the movement of piston I6 and also is connected with thethrottles 6| and 62, which are linked together so that they opensimultaneously. When the throttles 6| and 62 are opened rapidly, thepiston I6 moves to the left, lowering the pressure in chamber 68 whichallows piston 9| to move lever 64 anti-clockwise against the pressure ofspring 96, the movement of the piston 9| being transmitted theretothrough servomotor valve 61 and servomotor piston 65. A spring 88, tothe right of piston 65, serves to move the piston and thus thisservomotor valve 61 to the left.

A manually-operated lever 84 controls the movement of the piston valve45, compressing a spring 89 as it is moved toward the left. When thelever 84 is moved clockwise to unseat the valve 45, the high pressureoil passage 86, which communicates with the pipe 8 I, admits highpressure oil by this valve and through the unrestricted passage 94 tothe chamber 5| and then through passage 66 and restriction 95 to chamber68. This decreases the amount of fuel being pumped by pump 63 byincreasing the pressure in the chamber 68, which moves a piston 9| andthus lever 64 to the right, the object of this mechanism being merely tocut ofi the fuel. This is known as the idle cut-off control.

Normally oil under pressure from passage 86 enters chamber 5| through arestriction 92.

In Figure 3, the port 32 is controlled by a piston I04. This piston I04carries two pistons I05 and I06. These three pistons reciprocate in acylinder divided into four chambers I01, I08, I09 and I I0. Chamber I08is connected through the pipe III with the low pressure chamber 56connected connects the chamber I22 with the low pressure chamber 56. Thehigh pressure in the passage H2 is admitted through the passage 422 tothe left-hand side of the valve I ll. Valve I I1 is thus pushed to theright. Valve III carries on its extreme right hand a roller whichengages with the cam II9 similar to the valve I9 shown and described inFigure 1.

Chamber I 01 is connected through the pipe I23 with the chamber I24.Chamber I24 is connected through the restriction I25 with a highpressure pipe I26 leading from pump 55. This high pressure pipe I26 isconnected through the passage I21 with the cylinder I28 in whichreciprocates the valve I29. Valve I29 has a slabbedoff portion I30 whichforms with the partition I3| a variable opening leading from the chamberI24 to a low pressure chamber I33. This low pressure chamber I33communicates through the low pressure pipe I35 to the low pressurechamber 56. The valve I29 carries a. roller 34 which engages with thecam 36 as before, described to the oil pump 55. This oil pump 55 isprovided with a spring-loaded pressure relief valve II3. Chamber I09 isconnected through a pipe II4 to the high pressure oil pipe 2 leadingfrom pump 55. Chamber 0 is connected through the passage II5 to achamber II6. In this chamber there slides a valve I I! having aslabbed-off surface II8. This slabbed-off surface II8 makes a variableopening in the partition I39 betweeh chambers H6 and I22. High pressureoil in H2 is admitted to the chamber II6 through the restriction I20 sothat the pressure in the chamber 6 is below that of pressure in the pipeH2, and above that in the low pressure pipe I 2| which relative toFigure 1.

Operation (Figs. 1 and 2) 48, 49 and 50, also 66 and and so to chamber68. Piston 9| and servo valve 61 are thuspushed to the right,compressing spring 88; the piston 65 moves to the right by action of theservomotor valve 61 contained in it and a reduction in the fuel due tomovement of the lever 64 under infiuence of spring 96 occurs to bringthe system into equilibrium. The flow through the fuel venturi 38becomes lower and the pressure in chamber 31 becomes higher.

Cam 36 then descends and the valve 3| comes to a neutral position,closing port 32. The position of port 32 is determined by the cam I9which is positioned by the chamber I5 in accordance with the air fiowthrough the venturi II. By this means, the cams 36 and I9 determine themixture ratio at every air flow and at every altitude. When the densityresponsive device 2| causes the cam I9 to be moved normally to the planeof the paper, a different cam surface is substituted for the cam surfaceillustrated.

When the throttles BI and 62 approach the closed position. valve 46 andneedle 41 move to the left and the pressure in the chamber 68 is thusregulated empirically when the throttles are less than 10 open, 65 to 70being wide open. An empirical control of the fuel, when the throttlesare closed to below 10 open, is the most satisfactory solution of theproblem of controlling the mixture ratio, both at idle and immediatelyabove idle. Obviously, at the low air flows associated with smallthrottle openings, it is not possible to operate the automatic ratiocontrolling means, as the flow through the venturi I2 creates forces toofeeble to be effective.

The quantity of air flowing past the throttles 6I62 increases .as thearea of throttle opening increases so long as the drop across thethrottles is equal to or greater than half the atmospheric pressure. Theshape of the needle 41 is thus made to conform so that as the throttlesopen the valve 41 increases the opening in the partition 63. Thisdecreases the pressure in the chamber 6| and hence in the passage 66 andalso in the chamber 68, which allows the piston 9| to move to the left.The servomotor valve 6'! and piston 8| are thus moved to the left by thecompression spring 88. Or in other words, as the valve 47 moves to theright, the pressure in chamber 68 is reduced. As the servomotor valvemoves to the left, servomotor piston 65 also moves to the left so thatlever 64 also moves to the left so as to increase the discharge of thefuel pumps 63.

When the throttle is opened, the lever 85 being moved clockwise, piston16 is movedto the left, lowering the pressure in the chamber 71,therefore, lowering the pressure in the chamber 61. There is thus atemporary condition during which the spring 88 to the right of thepiston 65 causes a temporary increase in fuel flow by causing lever 64to be moved temporarily to the left to increase fuel flow. This takescare of acceleration.

The manual rotation of the shaft 42 moves the cam 36 normal to the planeof the paper by means of the lever 4 I. By this means a new cam surfaceis presented to the roller 34; hence, the ratio of fuel to air can bevaried manually just as it can be varied automatically by the element2I.

The control of the fuel injection pumps require considerable effort. Ifthe piston 9| engaged directly with the lever 64 without the secondservomotor piston 65 being interposed, the control would be irregulardue to the pressure required to operate the lever 64. The servomotor 65and valve 61 multiply many times the force exerted by the piston 9| sothat a comparatively insignificant effort on the part of the piston 9|produces a very definite force on the lever 64. The effect on thepressure in pipe 66 of the resistance of lever 64 would be such as tointerfere with the empirical control of the fuel during the first 10movement of the throttles 6| and 62.

In the operating connection betweenthe expanding chamber 31 and thesliding cam 36, between the expanding chamber I5 and the sliding cam I9and between the expanding chamber 2| and the sliding cam I9, I havefound it desirable to use large expanding chambers so as to obtainsufficient power to overcome friction so as to move the cam.Alternatively, if for reasons of space, it is desirable to userelatively small expanding chambers I5, 2I and 31, servomotors andservomotor valves will be interposed between the expanding chamber 3!and the sliding cam I9, between the expanding chamber I5 and the slidingcam I 9 and between the expanding chamber 2| and the sliding cam I9, forexample, such as the servomotor 65-61, which operates the lever 64.

Operation (Fig. 3)

Assuming that an excessive quantity of fuel, relative to the air flowingthrough venturi II, is flowing through the venturi 38, then the cam 36rises and the roller 34 is pushed to the right as the result of the oilpressure in the chamber I28. The slabbed-off portion I30 of valve I29then increases the opening past the partition I3I An increased fiow thenoccurs past the restriction I into the chamber I24. Therefore, there isan increased pressure drop at the restriction I25. The pressure in I23,which equals the pressure in II", is therefore reduced, and hence isreduced below that in chamber I III The valve I84 is thus moved to theleft. High pressure oil then flows down the pipe II 4 and through thechamber I09 and passage 32 to the passage 66, which increases thepressure in the chamber 68 of Figure 1, comopen are intended to,striction through 53 is not presses the spring 88 and permits the lever64 to move to the right, reducing the fuel flow in the fuel injectionsystem 63. With the arrangement shown in Figure 3, the cams 36 and I I9can be located anywhere on the engine and the piston valve I04 can belocated anywhere so that the problem of designing is simplified.

'Low speed empirical operation (Figs. 1 and 3) In both Figures 1 and 3,the valve controls the fuel-air ratio empirically when the throttles 6I62 approach the closed position for the reason that when the needle 41restricts the opening through 53, the pressure in the chamber Si isdominated by the flow of,operating fluid under pressure through therestriction 32. When the throttles 6I62 are more than 10 open, theneedle 41 moves so far to the right that the resufficient to, permit therestriction 92 to be effective. Hence, the mixture ratio becomes greatbecause the pressure in 68 falls and the lever 64 rotates anti-clockwiseunder the influence of the piston SI and spring 88, servomotor piston 65acting against the compression spring 96. This increases the flowthrough venturi 38 and establishes a rich mixture which causes the cam36 to rise and the automatic feature of this invention thereupon becomesoperative as the throttle is moved from approximately 10 open to whichis wide open. The throttle opening with be in the transition positionbetween the position for empirical control of the fuel flow and theposition of automatic fuel control by the two venturis 38 and I2.

What I claim is:

1. An empirical control for a fuel injection system comprising an airentrance, a throttle valve therein, a fuel injection system, a controllever therefor, a source of operating fluid under pressure, a passagetherefrom, a bypass therein, a needle valve connected to said throttlevalve and located in said bypass and adapted to permit said fluid toescape through said bypass, a restriction in said passage upstream fromsaid bypass, a servomotor, a fluid presure passage therefor connected tosaid passage and located downstream from said bypass, said servomotorbeing adapted to control said fuel injection system during the initialopening movement of said throttle.

2. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid therethrough to provide a, differential fluid pressure proportionalto air flow, a. source of liquid fuel under pressure, a fuel supplypassage connected thereto, a fuel injection system connected to saidpassage and adapted to inject fuel under pressure into said engine,control means for said fuel injection system, including means responsiveto the fuel flow in said fuel passage to provide a differential fluidpressure-proportional to the rate of fuel flow, an air cam movable bythe air differential pressure-a. fuel cam movable by the fueldifferential pressbre, a source of operating fluid under pressure, aservomotor valve therefor having two parts, one controlled by the aircam, the other controlled by the fuel cam, 21 servomotor, a fluidpassage connecting the servomotor with said two-part servomotor valve soas to control the movement of said servomotor, said control means forsaid fuel injection system being adapted to be controlled by saidservomotor whereby the quantity of fuel discharged by said fuelinjection the throttles as shown ,6.

passage responsive to air flow mately /1 to move the control for thefuel in- I jection system empirically.

3. Fuel control means for the fuel injection system of amulti-cylinderlntemal combustion engine comprising an air inductionpassage, means in said passage responsive to air flow therethrough toprovide a differential fluid pressure proportional to air flow, a sourceof liquid fuel under pressure, a fuel supply passage connected thereto,a fuel injection system connected to said passage and adapted to injectfuel under pressure into said engine, control means for said fuelinjection system, including means responsive to the fuel flow in saidfuel passage to provide a differential fluid pressure proportional tothe rate of fuel flow, an air cam movable by the air differentialpressure, a fuel cam movable by the fuel differential. pressure, asource of operating fluid under pressure, a servomotor valve thereforhaving two parts, one controlled by the air cam. theother controlled bythe fuel cam, a servomotor, a fluid passage connecting the servomotorwith said two-part servomotor valve so as to control the movement ofsaid servomotor, said control means for said fuel injection system beingadapted to be controlled by said servomotor whereby the quantity of fueldischarged by said fuel injection system is increased or decreaseddepending upon whether the measured rate of fuel flow is respectivelygreater or less than that required to provide' a predetermined variablefuel-air ratio for the measured rate of air flow and in which there isan'independently and manually Operated fuel cut oil. valve located so asto control the supply of operating fluid to said servomotor and tobypass the servomotor valve and adapted to move the control for the fuelinjection system so that it ceases to supply fuel to said internalcombustion engine.

4. Fuel control means for the fuel injection sysfuel injection system isincreased or decreased depending upon whether the measured rate of fuelflow is respectively greater or less than that required to provide a,predetermined variable fuelair ratio for the measured rate of air flowand in which the two-part servomotor valve comprises a hollowcylindrical outervalve, a piston slidably mounted within said cylinder,9, port in said cylinder, said piston having a, valve portion adaptedwhen in the neutral position to close said port, a high pressure portand a low pressure port in said cylindrical valve located on oppositesides of said valve portion whereby the movement of said valve portionrelative to said cylindricalvalve switches the operative pressure actingon said servomotor from high pressure to low pressure through said firstmentioned port and vice versa.

5. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid passage responsive to air flow therethrough to provide adifferential fluid pressure proportional to air flow, a source of liquidfuel under pressure, a fuel supply passage connected thereto, a fuelinjection system connected to said passage and adapted to inject fuelunder pressure into said engine, control means for said fuel injectionsystem, including means responsive to the fuel flow in said fuel passageto provide a differential fluid pressure proportional to the rate offuel flow, an air cam movable by the air differential pressure. a fuelcam movable by the fuel differential pressure, a source of operatingfluid under pressure, a servomotor valve therefor having two parts, onecontrolled by the air cam, the other controlled by the fuel cam, aservomotor, a fluid passage connecting the servomotor with said two-partservomotor valve so as to control the movement of said servomotor, saidcontrol means for said fuel injection system being adapted to becontrolled by said servomotor whereby the quantity of fuel discharged bysaid fuel injection system of a 'multi-cylinder internal combustionengine comprising an air induction passage, means in said passageresponsive to air flow therethrough to provide a differential fluidpressure proportional to air flow, a source of liquid fuel underpressure, a fuel supply passage connected thereto, a fuel injectionsystem connected to said passage and adapted to inject fuel underpressure into said engine, control means for said fuel injection system,including means responsive to the fuel flow in said fuel passage toprovide a. differential fluid pressure proportional to the rate of fuelflow, an air cam movable by the air differtem is increased or decreaseddepending upon whether the measured rate of fuel flow is respectivelygreater or less than that required to provide a predetermined variablefuel-air ratio for the measured rate of air flow and in which a throttleis provided in the air induction passage, a moving wall is connectedthereto, a chamber closed at one end by said moving wall, a connectionfrom said chamber to the fluid passage connecting the servomotor valveto the servomotor, said movin wall being adapted when the throttle issuddenly opened to temporarily reduce the pressure in said passage byexpanding the chamber so as to move said fuel injection control to theposition for an increase in fuel flow.

6. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid passage responsive to air flow therethrough to provide adifferentialflui'd pressure proportional to air flow, a source of liquidfuel under pressure, a fuel supply passage connected thereto, a fuelinjection system connected to said passage and adapted to inject fuelunder pressure into said engine, control means for said fuel injectionsystem, including means responsive to thefuel flow in said fuel passageto provide a differential fluid pressure proportional to the rate offuel flow, an air cam movable by the'air differential pressure, a fuelcam movable by the fuel differential pressure, a source of operatingfluid under pressure, a servomotor valve engaging with the air cam, asecond servomotor valve engaging with the fuel cam, a servomotor, apassage for fluid under pressure adapted to be jointly controlled byboth of said servomotor valves and to be connected with said servomotorso that the servomotor is operated by the fluid under pressure andcontrolled by the relative position of said cams, said control means forsaid fuel injection system being adapted to be controlled by saidservomotor whereby the quantity of fuel discharged by said fuelinjection system is increased or decreased depending upon whether themeasured rate of fuel flow is respectively greater or less than thatrequired to provide a predetermined variable fuel-air ratio for themeasured rate of air flow and in which a throttle is provided in the airinduction passage and a needle valve is connected thereto and located soas to control the supply of operating'fluid to said servomotor and tobypass the servomotor valve and adapted after the throttle is firstopened and until the throttle has been opened approximately to move thecontrol for the fuel injection system empirically.

7. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid passage responsive to air flow therethrough to provide adifferential fluid pressure proportional to air flow, a source of liquidfuel under pressure, a fuel supply passage connected thereto, a fuelinjection system connected to said passage and adapted to inject fuelunder pressure into said engine, control means for said fuel injectionsystem, including means responsive to the fuel flow in said fuel passageto provide a differential fluid pressure proportional to the rate offuel flow, an air cam movable by the air differential pressure, a fuelcam movable by the fuel differential pressure, a source of operatingfluid under pressure, a servomotor valve engaging with v the air cam, asecond servomotor valve engaging with the fuel cam, a servomotor, apassage for fluid under pressure adapted to be jointly controlled byboth of said servomotor valves and to be connected with said servomotorso that the servomotor is operated by the fluid under pressure andcontrolled by the relative position of said cams, said control means forsaid fuel injection system being adapted to be controlled by saidservomotor whereby the quantity of fuel discharged by said fuelinjection system is increased or decreased depending upon whether themeasured rate of fuel flow is respectively greater or less than thatrequired to provide a predetermined variable fuel-air ratio for themeasured rate of air flow and in which there is an independently andmanually operated fuel cut of! valve located so as to control the supplyof operating fluid to said servomotor and to bypass the servomotor valveand adapted to move the control for the fuel injection system so that itceases to supply fuel to said internal combustion engine.

8. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid passage responsive to air flow therethrough to provide adifferential fluid pressure proportional to air flow, a source of liquidfuel under pressure, a fuel supply passage-connected thereto, a fuelinjection system connected to said passage and adapted to inject fuelunder pressure into said engine, control means for said fuel injectionsystem, including means responsive to the fuel flow insaid fuel passageto proposition of said cams, said control means for said fuel injectionsystem being adapted to be controlled by said servomotor whereby thequantity of fuel discharged by said fuel injection system is increasedor decreased depending upon whether the measured rateof fuel flow isrespectively greater or less than that required to provide apredetermined variable fuel air ratio for the measured rate of air flowand in which acylinder divided into four chambers by three pistonsconnected together, one end chamber being con-t nected through a passagewith the servomotor valve engaging with the air cam, the other end beingconnected through a passage with the servomotor valve engaging with thefuel cam, one of the two intermediate chambers being connected to thefluid under pressure, a central port in said cylinder, the middle of thethree pistons being adapted to control said central port, said portbeing connected with said servomotor for the purpose described.

9. Fuel control means for the fuel injection system of a multi-cylinderinternal combustion engine comprising an air induction passage, means insaid passage responsive to air flow therethrough to provide adifferential fluid pressure proportional to air flow, a sourc of liquidfuel under pressure, a fuel supply passage connected thereto, a fuelinjection system connected to said passage and adapted to inject fuel'under pressure into said engine, control means for said fuel injectionsystem, including means responsive to the fuel flow in said fuel passageto provide a differential fluid pressure proportional to the rate offuel flow, an air cam movable by the air differential pressure, a fuelcam movable by the fuel differential pressure, a source of operatingfluid under pressure, a servomotor valve engaging with the air cam, asecond servomotor valve engaging with the fuel cam, a servomotor, apassage for fluid under pressure adapted to be jointly controlled byboth of said servomotor valves and to be connected with said servomotorso that the servomotor is operated by the fluid under pressure andcontrolled by the relative position of said cams, said control means forsaid fuel injection system being adapted to be controlled by saidservomotor whereby the quantity of fuel discharged by said fuelinjection sys- I tern is increased or decreased depending upon whetherthe measured rate of fuel flow is respectively reater or less than thatrequired to pro-' Y duce the pressure in said passage-by expanding thechamber so as to move, seidfuel injection control to, the-position foran increase in fuel flow.

10. Fuel control magi for the fuel injection system of amulti-cylinder-internal combustion engine. comprising an air inductionpassage, means in said passage responsive to air flow therethrough toprovide a differential fluid pressure proportional to. airflow, a sourceof liquid fuel diiferentialpressure, a source of operating fluid underpressure, a servomotor valve engaging with the air cam. a. secondservomotorvalve engaging with the fuel .cam, a servomotor,,a passage forfluid under pressure adapted to be jointly controlled by both of saidservomotor valves and to be connected withsaid servomotor sothat .theservomotor is operated by the fluid under, pressure .and controlled bythe relative position of'said cams, said. control means for said fuelinjection system being adapted to be controlled by saidservomotorwhereby the quantity of fuel discharged by said fuelinjectionsystemis increased or decreased. depending upon whether. the measuredrate of fuel flow is .re-

spectivelygreater or lessthan that required to 35 provide apredetermined variable fuel-air ratio for the measured rate of airflowand in which the servomotor valve engaging withsaid air-cam ispressedinto engagement therewith,'said operatingfluid acting onthe endof saidservornotor 4o 2 281,411

valve soastoprovide said pressure.

11. Fuel control means for the fuel injection system of .a.multi-cylinder. internal combustion engine comprising an air inductionpassage, means in saidpassage responsive to airflow therethrough toprovide a diflerential fluid pressure proportionalgtdairflow, a-sourceof liquid 12 fuel under pressure, a fuel supply passage connectedthereto, a fuel injection system connected to said passage and adaptedto inject fuel under pressure into said engine, control means for saidfuel ,injection system, including means responsive to the fuel flow insaid fuel passage to provide a differential fluid pressure proportionalto the rate of fuel flow, an air cam movable by the air differentialpressure, a fuel cam movable by the fuel differential pressure, a sourceof operating fluid under pressure, a servomotor valve engaging with theair cam, a second servomotor valve engaging with the fuel cam. aservomotor, a passage for fluid under pressure adapted to be jointlycontrolled by both of said servomotor valves and to be connected withsaid servo motor so that the servomotor is operated by the fluid underpressure and controlled by the relative position of said cams, saidcontrol means for said fuel injection system being adapted to becontrolled ,by said servornotor'whereby the quantity of fuel dischargedby said fuel injection system is'increased or decreased depending uponwhether the measured rate of fuel flow is respectively greater or lessthan that required to provide a predetermined variable fuel-air ratiofor the measured rate of air flow and in which the servomotor valveengaging with said fuel camis pressed into engagement therewith, saidoperating fluid acting on the end of said servomotor valve so as toprovide said pressure.

- JOHN P. CAlVlPBEIL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Campbell April 28, 1942 2,341,257Wunsch Feb. 8, 1944 1,975,624 Simmen Oct. 2, 1934 2,132,445 SchweizerOct, 11, 1938 FOREIGN PATENTS Number Country Date 113,026 Australia May2, 1941

